Yeah, I played the siren at first. Then I dueled my room mate. Then I realized that I just wasted several hours leveling up a character with shitty skills. Basically, you turn invisible and run fast...

That's it. No shooting guns, no melee attacks while stealth, just running. When you go in and out, you do a little bit of damage, but not enough to be useful. Brick all the way.

Oh, yeah. Just tap it. But it does come in handy when you need to fight something that's chasing you and you need a specific weapon on the ground to kill it. Just run by and hold X down and booyaka. It's gotten me out of a lot of bad situations...

As for the world, there are different sections. Each one, if you're on foot, is pretty big. When driving it's a bit easier to get across, but it's definitely not quick. The only loading screens you see are between different areas--so a bunch of enemies could chase you into a town if they wanted. XD Funny shit. And the NPCs don't do anything. They just stand there...while a giant Skag is pummeling you...

You get missions from NPCs (half of which advance the storyline), or you can go to the Bounty Board where you get missions from random other people. Or you can go around and level without doing missions. Just make sure you're in the right area and you don't see enemies with skulls by their names. XD I learned that the hard way (didn't look at the warning it gave me) and got destroyed. Never try to snipe an enemy 7 levels higher than you. NEVER.

Sometimes I just go GTA--get in a vehicle and start crushing things. Unfortunately the environment isn't destructive (or movable), so you can't break objects...Maybe they'll fix that with the next game, if they make one.